Apparatus and/or method of controlling timing of servo pulses and disk drive using the method

ABSTRACT

Provided is a method and apparatus for adaptively controlling the timing of servo pulses in a disk drive in consideration of the amount of spindle jitter generated when a disk rotation speed is changed. The method of controlling the timing of a sector pulse for write operation includes: measuring a spindle jitter value in a data write mode; generating a timing correction value of a sector pulse, which indicates a position of a sector where data is written, according to the measured spindle jitter value; and generating a sector pulse by reflecting the timing correction value of the sector pulse.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Korean Patent Application No.10-2004-0038192, filed on May 28, 2004, in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus for controllingthe timing of servo pulses in a disk drive, and more particularly, to amethod and apparatus for adaptively controlling the timing of servopulses in consideration of the amount of jitter generated when arotational speed of a disk is changed.

2. Description of the Related Art

In general, hard disk drives (HDDs) used in computer systems are datastorage devices that reproduce data recorded on a disk or record data onthe disk using a magnetic head. As the capacity, density, and size ofHDDs increase, bits per inch (BPI), which are a measure of the recordingdensity in a rotational direction of a disk, and tracks per inch (TPI),which are a measure of the recording density in a radial direction ofthe disk, are also increasing. Accordingly, HDDs require a more delicatemechanism.

HDDs read servo information at regular time intervals from a disk, whichrotates at a constant speed, using a transducer (referred to as a head),identify a location of a data sector based on the read servoinformation, and perform write or read operation.

Referring to FIG. 1, a pattern of servo information recorded on a diskof an HDD contains a preamble, a servo address/index mark SAM/SIM, agray code, and burst signals A, B, C, and D.

The preamble has a gap before a servo sector, thereby providing aconstant timing margin. The SAM represents a starting point of the servosector, and the SIM provides information on a revolution of the disk.The gray code provides identification (ID) information of each track,and the burst signals are used to control a position of a head.

If a disk rotation speed in the HDD is constant, servo information isdetected at regular time intervals. However, if the HDD wobbles due toan external impact or the like and the disk rotation speed is changed,the timing at which the servo information is detected is changed. If awrite operation is performed when the timing is changed, a position of asector where data is written is also changed.

In general, the value of spindle jitter (or referred to as spin jitter)represents a difference between a current rotational speed of a disk anda target disk rotation speed. If a spindle jitter value is “0”, the SAMis detected at regular time intervals. However, if it is not “0”, theSAM is detected at shorter or longer intervals.

FIG. 2A illustrates that if data is recorded and reproduced when aspindle jitter value is “0”, a position of a sector pulse and a positionof a sector where the data is recorded or reproduced are exactlyaligned.

FIG. 2B illustrates that if data is recorded when a spindle jitter valueis a negative number and the data is reproduced when a spindle jittervalue is 0, a position of a sector pulse for data read operation and aposition of a sector where the data is recorded are misaligned.

FIG. 2C illustrates that if data is recorded when a spindle jitter valueis a positive number and the data is reproduced when a spindle motor is“0”, a position of a sector pulse for data read operation and a positionof a sector where the data is recorded are misaligned.

Methods for correcting the timing of servo pulses including a sectorpulse and a servo gate pulse according to the amount of generatedspindle jitter have not been developed yet. Accordingly, if spindlejitter is excessively generated in a data write mode, data writeoperation cannot be performed normally. If data is written in thisstate, the possibility of errors increases in a data read mode since aposition of a sector pulse and a position of a sector where the data iswritten are misaligned during reproduction.

Further, the possibility of errors increases even when spindle jitter isexcessively generated in a data read mode, since a position of a sectorpulse and a position of a sector where the data is written aremisaligned.

Also, if the amount of spindle jitter is relatively large, a SAM signalexceeds a position of a servo gate pulse, resulting in a failure todetect the SAM signal normally.

SUMMARY OF THE INVENTION

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be apparentfrom the description, or may be learned by practice of the invention.

The present invention provides a method for controlling the timing ofservo pulses including a sector pulse and a servo gate pulse to correctthe servo pulses based on the amount of generated spindle jitter andperform stable write and read operation, and a disk drive using themethod.

According to an aspect of the present invention, there is provided amethod of controlling the timing of a sector pulse for write operationin a disk drive, the method including the operations of: measuring aspindle jitter value in a data write mode; generating a timingcorrection value of a sector pulse, which indicates a position of asector where data is written, according to the measured spindle jittervalue; and generating a sector pulse according to the timing correctionvalue of the sector pulse.

According to another aspect of the present invention, there is provideda method of controlling the timing of a sector pulse for read operationin a disk drive, the method including the operations of: measuring aspindle jitter value in a data read mode; generating a timing correctionvalue of a sector pulse, which indicates a position of a sector wheredata is read, according to the measured spindle jitter value; andgenerating a sector pulse according to the timing correction value ofthe sector pulse.

According to still another aspect of the present invention, there isprovided a method of controlling the timing of a servo gate pulse in adisk drive, the method including: measuring a spindle jitter value in adata write mode and a data read mode; and correcting the timing of aservo gate pulse, which is used for obtaining servo information,according to the measured spindle jitter value.

According to yet another aspect of the present invention, there isprovided a disk drive that is a data storage device, the disk driveincluding: a host interface, which transmits or receives data to or froma host device; a controller, which measures a spindle jitter value in adata write mode and a data read mode, and compensates for the timing ofa predetermined servo control signal according to the measured spindlejitter value; and a writing/reading circuit, which writes data, which isreceived via the host interface, on a disk or reads data from the diskaccording to the predetermined servo control signal generated by thecontroller.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a diagram illustrating a pattern of servo information writtenon a disk of a conventional hard disk drive (HDD);

FIGS. 2A through 2C are timing diagrams of major signals for explainingtiming misalignment due to spindle jitter in the conventional art;

FIG. 3 is a top plan view of a head disk assembly (HDA) of a disk driveaccording to an aspect of the present invention;

FIG. 4 is an electrical circuit diagram of a disk drive using a methodof controlling the timing of servo pulses according to an aspect of thepresent invention;

FIG. 5 is a flow chart of a method of controlling the timing of a sectorpulse for write operation according to an aspect of the presentinvention;

FIG. 6 is a flow chart of a method of controlling the timing of a sectorpulse for read operation according to an aspect of the presentinvention;

FIG. 7 is a flow chart of a method of controlling the timing of a servogate pulse according to an aspect of the present invention; and

FIGS. 8A through 8C are timing diagrams of major signals for explainingtiming compensation of the sector pulse for write operation according toan aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below to explain the presentinvention by referring to the figures.

A hard disk drive (HDD) is a combination of electrical circuits and ahead disk assembly (HDA) composed of mechanical components.

FIG. 3 shows an HDA of an HDD according to an aspect of the presentinvention.

An HDA 10 includes at least one magnetic disk 12, which is rotated by aspindle motor 14. The disk drive further includes a transducer 16, whichis slightly spaced from a disk surface 18.

The transducer 16 can read or write information on the rotating disk 12sensing a magnetic field of the disk 12 or magnetizing the disk 12.Although the transducer 16 is illustrated as a single body in FIG. 3, itshould be appreciated that the transducer 16 is divided into a writetransducer for magnetizing the disk 12 and a separate read transducerfor sensing the magnetic field of the disk 12. The read transducer maybe constructed from a magneto-resistive element (MR). The transducer 16is typically referred to as a head.

The transducer 16 may be integrated with a slider 20. The slider 20generates an air bearing between the transducer 16 and the disk 12surface. The slider 20 is coupled to a head gimbal assembly 22. The headgimbal assembly 22 is attached to an actuator arm 24 having a voice coil26. The voice coil 26 is positioned adjacent to a magnetic assembly 28to define a voice coil motor (VCM) 30. If current is supplied to thevoice coil 26, a torque for rotating the actuator arm 24 about a bearingassembly 32 is generated. The actuator arm 24 rotates to cause thetransducer 16 to traverse the disk surface 18.

Information is typically stored in annular tracks on the disk 12. Eachtrack 34 generally includes a plurality of sectors. Each sector includesa data field and an identification field. The identification fieldcontains a gray code that identifies sectors and tracks (cylinder). Thetransducer 16 traverses the disk 12 surface to read or write informationon the track.

FIG. 4 is a circuit diagram of an electrical system 40 for controllingan HDD. The electrical system 40 includes a controller 42, which isconnected to the transducer 16 via a read/write (RAN) channel circuit 44and a pre-amp circuit 46 according to an aspect of the presentinvention.

A digital signal processor (DSP), a microprocessor, a micro-controller,or the like can be used as the controller 42. The controller 42 controlsthe R/W channel circuit 44 to read information from the disk 12 or writeinformation on the disk 12. The controller 42 generates a sector pulse,which indicates a position of a sector where data is written in a writemode and a position of a sector where data is read in a read mode, andalso generates a servo gate pulse for obtaining a servo mark addresssignal.

The controller 42 is also connected to a VCM driving circuit 48 thatsupplies driving current to the voice coil 26. The controller 42supplies a control signal to the VCM driving circuit 48 to control theexcitation of the VCM 30 and the movement of the transducer 16.

Firmware for controlling the disk drive and various control data arestored in a memory 50.

First, the operation of a conventional disk drive will be explainedbelow.

In a data read mode, a pre-amp circuit 46 amplifies an electrical signalsensed by the transducer 16 from the disk 12 to enable signalprocessing. Then, the R/W channel circuit 44 codes the signal read fromthe disk into a digital signal according to the timing of a sector pulsefor read operation generated by the controller 42, converts the digitalsignal into stream data, and transmits the stream data to a host device(not shown) via a host interface circuit 54.

Next, in a write mode, the disk drive receives data from the host devicevia the host interface circuit 54. An internal buffer (not shown) of theinterface circuit 54 temporarily stores the received data andsequentially outputs the stored data to the R/W channel circuit 44. TheR/W channel circuit 44 converts the data into a binary data streamsuitable for a writing channel of the disk 12. At a time when a sectorpulse for a write operation is generated, the binary data stream isamplified by the pre-amp circuit 46, and then written on the disk 12 bythe transducer 16.

The controller 42 according to an aspect of the present invention isdesigned to measure a spindle jitter value in a data write mode and/or adata read mode, and corrects the timing of the sector pulse and theservo gate pulse according to the measured spindle jitter value. Here,the spindle jitter value is obtained by measuring a servo address mark(SAM) detection cycle and calculating a difference between the measuredcycle and a standard cycle. Methods of correcting the timing of thesector pulse and the servo gate pulse will be explained respectively indetail below with reference to flow charts in FIGS. 5 through 7.

The sector pulse indicates the timing at which data is written on atrack in the data write mode, and indicates the timing at which data isread in the data read mode. The servo gate pulse is a window signal fordetecting a SAM.

Among the methods of controlling the timing of servo pulses according toan aspect of the present invention, a method of controlling the timingof the sector pulse in the write mode will be first explained in detailwith reference to the circuit diagram of FIG. 4 and the flow chart ofFIG. 5.

In operation S501, the controller 42 determines whether a write commandis received from the host device through the host interface circuit 54.

If it is determined in operation S501 that the write command isreceived, the process goes to operation S502. In operation S502, thecontroller 42 measures a spindle jitter value ΔJ_(i) using a SAMdetection cycle.

In operation S503, the measured spindle jitter value ΔJ_(i) is comparedwith a first threshold value TH1. Here, the first threshold value TH1 isa maximum allowable spindle jitter value that does not cause functionalproblems without timing correction of servo pulses.

If it is determined in operation S503 that the measured spindle jittervalue ΔJ_(i) is less than or equal to the first threshold value TH1, theprocess goes to operation S504. In operation S504, a timing correctionvalue α_(i) of the sector pulse for write operation is set to “0”. Thismeans that spindle jitter has not been generated to a point where thetiming of the sector pulse for the write operation needs to becorrected.

If it is determined in operation S503 that the measured spindle jittervalue ΔJ_(i) is greater than the first threshold value TH1, the processgoes to operation S505. In operation S505, the measured spindle jittervalue ΔJ_(i) is compared with a second threshold value TH2. Here, thesecond threshold value TH2 is a maximum allowable spindle jitter valuethat can be compensated through timing correction.

If it is determined in operation S505 that the spindle jitter valueΔJ_(i) is greater than or equal to the second threshold value TH2, theprocess goes to operation S509. In operation S509, the write operationthat is being executed is stopped, and the disk is rotated apredetermined number of times, and then, a write retry mode is performedto execute the write operation again.

If it is determined in operation S505 that the measured spindle jittervalue ΔJ_(i) is less than the second threshold value TH2, the processgoes to operation S506. In operation S506, a timing correction valueα_(i) for correcting a position of the sector pulse for write operationis calculated. Here, the timing correction value α_(i) of the sectorpulse for the write operation is designed to be proportional to themeasured spindle jitter value ΔJ_(i).

In operation S507, a sector pulse for the write operation is generatedby reflecting the timing correction value α_(i) of the sector pulse forthe write operation obtained through operations S504 and S506.

In operation S508, the data write operation is executed from a time whenthe sector pulse for the write operation is generated in operation S507.

FIG. 8A is a timing diagram illustrating that the sector pulse for thewrite operation is generated in a 200 clock cycle if the measured jittervalue is less than the first threshold value TH1 and the timingcorrection value α_(i) is set to “0”.

FIG. 8B is a timing diagram illustrating that the sector pulse for writeoperation is corrected in a 205 clock cycle if the measured spindlejitter value is a negative number between the first threshold value TH1and the second threshold value TH2 and the timing correction value α_(i)is +5. It can be seen that a position of a sector pulse for readoperation, which is generated in a 200 clock cycle, when the spindlejitter value is “0” during a data read operation is exactly aligned witha position of data written by a sector pulse for write operation, whichis corrected in a 205 clock cycle.

FIG. 8C is a timing diagram illustrating that the sector pulse for writeoperation is corrected in a 195 clock cycle if the measured spindlejitter value is a positive number between the first threshold value TH1and the second threshold value TH2 and the timing correction value α_(i)is −5. It can be seen that a position of a sector pulse for readoperation, which is generated in a 200 clock cycle, when the spindlejitter value is “0” during the data read operation is exactly alignedwith a position of data written by a sector pulse for write operation,which is corrected in a 195 clock cycle.

Next, among the methods of controlling the timing of servo pulsesaccording to the present invention, a method of controlling the timingof a sector pulse in a read mode will be explained in detail withreference to the circuit diagram of FIG. 4 and the flow chart of FIG. 6.

In operation S601, the controller 42 determines whether a read commandis received from the host device through the interface circuit 54.

If it is determined in operation S601 that the read command is received,the process goes to operation S602. In operation S602, the controller 42measures a spindle jitter value ΔJ_(i) using a SAM detection cycle.

In operation S603, the measured spindle jitter value ΔJ_(i) is comparedwith a first threshold value TH1. Here, the first threshold value TH1 isa maximum allowable spindle jitter value that does not cause functionalproblems without timing correction in the HDD.

If it is determined in operation S603 that the measured spindle jittervalue ΔJ_(i) is less than or equal to the first threshold value TH1, theprocess goes to operation S604. In operation S604, a timing correctionvalue β_(i) of a sector pulse for read operation is set to “0”. Thismeans that spindle jitter has not been generated to a point where thetiming of the sector pulse for the read operation needs to be corrected.

If it is determined in operation S603 that the measured spindle jittervalue ΔJ_(i) is greater than the first threshold value TH1, the processgoes to operation S605. In operation S605, the measured spindle jittervalue ΔJ_(i) is compared with a second threshold value TH2. Here, thesecond threshold value TH2 is a maximum allowable spindle jitter valuethat can be compensated through timing correction.

If it is determined in operation S605 that the measured spindle jittervalue ΔJ_(i) is greater than or equal to the second threshold value TH2,the process goes to operation S609. In operation S609, the readoperation that is being executed is stopped, and the disk is rotated apredetermined number of times, and then, a read retry mode is performedto execute the read operation again.

If it is determined in operation S605 that the measured spindle jittervalue ΔJ_(i) is less than the second threshold value TH2, the processgoes to operation S606. In operation S606, a timing correction valueβ_(i) for correcting a position of the sector pulse for read operationis calculated. Here, the timing correction value β_(i) of the sectorpulse for the read operation is designed to be proportional to themeasured spindle jitter value ΔJ_(i).

In operation S607, a sector pulse for the read operation is generated byreflecting the timing correction value β_(i) of the sector pulse for theread operation obtained through operations S604 and S606.

In operation S608, the data read operation is executed from a time whenthe sector pulse for the read operation is generated in operation S607.

In this manner, although spindle jitter is generated, the timing of thesector pulses for write and read operations can be exactly correctedaccording to the value of the generated spindle jitter.

Finally, among the methods of controlling the timing of servo pulsesaccording to an aspect of the present invention, a method of controllingthe timing of a servo gate pulse in a write mode and a read mode will beexplained in detail with reference to the circuit diagram of FIG. 4 andthe flow chart of FIG. 7.

In operation S701, the controller 42 determines whether a write commandor read command is received from the host device through the hostinterface circuit 54.

If it is determined in operation S701 that the write command or readcommand is received, the process goes to operation S702. In operationS702, the controller 42 measures a spindle jitter value ΔJ_(i) using aSAM detection cycle.

Next, in operation S703, the timing of a servo gate pulse, which is usedfor obtaining a SAM, is corrected by reflecting the measured spindlejitter value ΔJ_(i). The method of correcting the timing of the servogate pulse can be performed using the same principle as used in theabove methods of correcting the timing of the sector pulses.

Next, in operation S704, the data read operation or data write operationis performed.

In this manner, although spindle jitter is generated, the timing of theservo gate pulse can be exactly corrected according to the value of thegenerated spindle jitter.

Since the timing of the sector pulse and the servo gate pulse iscorrected according to the value of the generated spindle jitteralthough spindle jitter is generated in the data write and read modes,the data write and read operations can be executed without errors evenwhen the rotational speed of the disk is changed.

The present invention can be executed as a method, an apparatus, asystem, and so on. When the present invention is executed as software,elements of the present invention are code segments that performindispensable operations. The programs or code segments can be stored ina processor-readable medium or transmitted by a computer data signalembodied in a carrier wave over a transmission medium or a communicationnetwork. The processor-readable medium includes any medium that canstore or transmit information. The processor-readable medium may includean electronic circuit, a semiconductor memory device, a read-only memory(ROM), a flash memory, an erasable ROM (EROM), a floppy disk, an opticaldisk, a hard disk, a fiber-optic medium, a radio frequency (RF) networksystem, etc. The computer data signal includes any signal that can betransmitted over a transmission media, e.g., an electronic networkchannel, an optical fiber, air, an electronic system, and an RF network.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.Accordingly, it is obvious that the present invention is not limited tospecific constructions or arrangements but can be applied to variouskinds of disk drives including HDDs.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A method of controlling the timing of a sector pulse for a writeoperation in a disk drive, the method comprising: measuring a spindlejitter value; generating a timing correction value of a sector pulse,which indicates a position of a sector where data is written, accordingto the measured spindle jitter value; and generating a sector pulse inaccordance with the timing correction value of the sector pulse.
 2. Themethod of claim 1, wherein the spindle jitter value is generatedmeasuring a servo address mark detection cycle.
 3. The method of claim1, wherein the operation of generating the timing correction valuecomprises: comparing the measured spindle jitter value measured with afirst threshold value; if it is determined that the measured spindlejitter value is less than or equal to the first threshold value, settingthe timing correction value of the sector pulse to “0”; if it isdetermined that the measured spindle jitter value is greater than thefirst threshold value, comparing the measured spindle jitter value witha second threshold value; and if it is determined that the measuredspindle jitter value is less than the second threshold value,calculating a timing correction value of a sector pulse that correspondsto the measured spindle jitter value, and if it is determined that themeasured spindle jitter value is greater than or equal to the secondthreshold value, performing a write retry mode.
 4. A method ofcontrolling the timing of a sector pulse for a read operation in a diskdrive, the method comprising: measuring a spindle jitter value;generating a timing correction value of a sector pulse, which indicatesa position of a sector where data is read, according to the measuredspindle jitter value; and generating a sector pulse in accordance withthe timing correction value of the sector pulse.
 5. The method of claim4, wherein the spindle jitter value is generated measuring a servoaddress mark detection cycle.
 6. The method of claim 4, wherein theoperation of generating the timing correction value comprises: comparingthe measured spindle jitter value with a first threshold value; if it isdetermined that the measured spindle jitter value is less than or equalto the first threshold value, setting the timing correction value of thesector pulse to “0”; if it is determined that the measured spindlejitter value is greater than the first threshold value, comparing themeasured spindle jitter value with a second threshold value; and if itis determined that the measured spindle jitter value is less than thesecond threshold value, calculating a timing correction value of asector pulse that corresponds to the measured spindle jitter value, andif it is determined that the measured spindle jitter value is greaterthan or equal to the second threshold value, performing a read retrymode.
 7. A method of controlling the timing of a servo gate pulse in adisk drive, the method comprising: measuring a spindle jitter value in adata write mode and a data read mode; and correcting the timing of aservo gate pulse, which is used for obtaining servo information,according to the measured spindle jitter value.
 8. The method of claim7, wherein the servo information includes a servo address mark signal.9. A disk drive that is a data storage device, the disk drivecomprising: a host interface, which transmits or receives data to orfrom a host device; a controller, which measures a spindle jitter valuein a data write mode and a data read mode, and compensates for thetiming of a predetermined servo control signal according to the measuredspindle jitter value; and a writing/reading circuit, which writes data,which is received via the host interface, on a disk or reads data fromthe disk according to the predetermined servo control signal generatedby the controller.
 10. The disk drive of claim 9, wherein the servocontrol signal includes a sector pulse that indicates a position of asector where data is written and a position of a sector where data isread.
 11. The disk drive of claim 9, wherein the servo control signalincludes a servo gate pulse for obtaining a servo address mark signal.12. The disk drive of claim 9, wherein the spindle jitter value isgenerated measuring a servo address mark detection cycle.
 13. A methodof controlling the timing of a sector pulse for disk drive, the methodcomprising: measuring a spindle jitter value; generating a timingcorrection value of a sector pulse, which indicates a position of asector where data is written, according to the measured spindle jittervalue; and generating a sector pulse using the timing correction valueof the sector pulse, wherein the operation of generating the timingcorrection value comprises: comparing the measured spindle jitter valuemeasured with a threshold value; if it is determined that the measuredspindle jitter value is less than or equal to the threshold value,setting the timing correction value of the sector pulse to the thresholdvalue; if it is determined that the measured spindle jitter value isgreater than the threshold value, and performing a write retry mode. 14.A disk controller controlling the timing of a sector pulse for writeoperation in a disk drive, the disk controller comprising: a spindlejitter value generator to generate a spindle jitter value in a datawrite mode; and a sector pulse timing correction value generator togenerate a sector pulse timing correction value a, which indicates aposition of a sector where data is written, according to the spindlejitter value.
 15. A disk controller to control the timing of a sectorpulse for write operation in a disk drive, the disk controllercomprising: a spindle jitter value detector; a timing correction valueof a sector pulse generator to generate a sector pulse, which indicatesa position of a sector where data is written, according to the measuredspindle jitter value; and to generate a sector pulse using the timingcorrection value of the sector pulse, wherein the operation ofgenerating the timing correction value comprises: comparing the measuredspindle jitter value measured with a threshold value; if it isdetermined that the measured spindle jitter value is less than or equalto the threshold value, setting the timing correction value of thesector pulse to the threshold value; if it is determined that themeasured spindle jitter value is greater than the threshold value, andperforming a write retry mode.
 16. A computer having the disk controllerof claim
 14. 17. A method of controlling the timing of a sector pulsefor write and/or read operation in a disk drive, the method comprising:measuring a spindle jitter value, which indicates a position of a sectorwhere data is written; and generating a timing correction value of asector pulse according to the measured spindle jitter value
 18. Themethod of claim 17, further comprising: generating a sector pulse inaccordance with the timing correction value of the sector pulse.